Laubender



Feb. 21, 1956 LAUBENDER 2,735,260

MEANS FOR PREVENTING THE FORMATION OF OIL CARBON DEPOSITS ON THE INNER SURFACE OF THE ExHAusT PORT IN A TWO-CYCLE nTEsEL ENGINE Filed July 24, 1953 INVf/WOP LUDWG LAUBENDEE A M s m A United States Patent Ludwig Laubeuder, Traustein, Germany, assignor to F. A. Krauss-Mafiei A. G., Munich, Allach, Germany Application July 24, 1953, Serial No. 370,087

Claims priority, application Germany August 1, 1952 4 Claims. (Cl. 60-29) The present invention relates to means for preventing the formation of oil carbon deposits on the inner surface of the exhaust port adjoining the cylinder wall of a two-cycle diesel engine.

In two-cycle diesel engines, a certain amount of lubricating oil which adheres to the reciprocating piston is carried along to the cylinder wall, being partially stripped off from the piston as it passes the exhaust port by the edges of the port and thus deposited on a portion of the inner surface of the exhaust port away from the combustion space of the cylinder. The lubricant is subjected to a chemical conversion by the action of the hot combustion gases, oil carbon thus being formed which accumulates as a deposit firmly adhering to the inner surface of the port. In the course of the operation of the diesel engine, this deposit of oil carbon grows, increasing in thickness in a tapering manner into the exhaust duct, starting from the side of the port adjacent to the cylinder. It adheres particularly strongly in the ports after it has spread over the entire width of the port so that it is held by the side surfaces. The result of the formation of this oil deposit is a reduction of the effective cross sectional area of the port passages which impairs the scavenging of the cylinder and the power output of the diesel engine is thereby reduced. It is therefore necessary to remove this oil carbon deposit periodically from the exhaust ports after relatively short periods of operation of the diesel engine.

The present invention has for an object, the provision of means for preventing the formation of these oil carbon deposits on the inner surface of the exhaust port adjoining the cylinder, without any accompanying detrimental elfect on the lubrication or sealing of the piston. This is accomplished in such a manner that the oil carbon is burned oh by the hot combustion gases as they leave the cylinder, the hot gases being deflected to the places where the deposits would otherwise accumulate and the deposit forming residues are carried away by the exhaust gases and passed out through the exhaust ducts.

Inasmuch as the oil carbon deposits are continuously removed as rapidly as they are produced, in the course of each piston stroke, no large quantities of oil carbon deposits can accumulate in the exhaust ports thereby avoiding any clogging of the exhaust ports with the accompanying reduction in the output power of the diesel engine.

Two embodiments of the invention are shown diagramatically in the drawing in which:

Figure 1 is a fragmentary sectional view in elevation of a diesel engine cylinder embodying the invention.

Figure 2 is a view similar to Fig. 1 showing a modified form of the invention.

Referring to Fig. 1, the cylinder wall 1 of a portcontrolled two-cycle diesel engine is shown provided with a scavenging port 2 and an exhaust port 3 which are controlled in conventional manner by the usual reciprocating piston (not shown). When the piston closes the exhaust port 3, a certain amount of the lubricating oil supplied to the cylinder wall is carried along by the piston and is cumulatively deposited on the lower inner surfaces 5 of the exhaust ducts adjacent to the ports 3 and farthest away from the combustion space 4, of the cylinder. This oil becomes coked by the action of the hot combustion gases.

As shown in Figure 1, straight continuous exhaust gas guiding burn-off ducts 6 are provided which by-pass the upper side of the exhaust port adjacent to the combustion space for continuously removing the oil carbon deposited at 5, said ducts being directed obliquely to the axis of the cylinder and toward the portions 5 of the exhaust ducts adjacent to the exhaust ports 3 where carbon deposits would otherwise accumulate. The burn-olf ducts 6 communicate directly between the upper walls of the exhaust ducts adjacent to the cylinder wall 1 and the portion of the combustion space 4 immediately above the exhaust ports 3. The piston, which moves downwardly during the working stroke, uncovers the openings of the burn-off ducts 6 before the exhaust port 3 is uncovered so that the burning gases can flow directly through said ducts at relatively high pressure and high velocity to the places of carbon accumulation and burn away any oil carbon deposits which may have formed. Thus, large deposits of oil carbon cannot accumulate. The gaseous and solid finely granular combustion products of the oil carbon are carried away by the main exhaust gases discharging in the usual manner through the exhaust ducts when the exhaust port is uncovered by the further downward movement of the piston.

Figure 2 shows a modified embodiment of the invention in which the burn-off ducts 6 are replaced by a downwardly projecting exhaust gas guiding nose member 7 located adjacent to the upper edge of the exhaust port 3, facing the combustion space 4. The inclined surface of nose 7 communicates directly with the combustion space 4 upon the initial opening of exhaust port 3 by the downwardly moving piston, and the burning combustion gases are deflected and directed by this inclined surface to the location 5 where the carbon deposits would otherwise accumulate in the exhaust duct. In this case, the burn-off passage is defined in part by the surface of the nose 7 which is located adjacent to and inclined obliquely to the axis of the cylinder wall 1, the remainder of the burn-off passage being defined by the lateral surface of the piston. This burns away any carbon deposit which may have formed during the preceding piston stroke.

While I have shown what I believe to be the best embodiments of my invention, what I desire to secure by Letters Patent of the United States is the invention as defined in the appended claims.

What is claimed is:

1. Carbon deposit formation preventing means for an internal combustion engine comprising a cylinder, an exhaust port formed in the wall of said cylinder, an exhaust duct communicating with said port, and means defining a combustion space Within said cylinder and adjacent to said port, said formation preventing means comprising exhaust gas guiding means defining a continuous burn-off passage which communicates directly between a portion of said exhaust duct immediately adjacent to said port and a portion of said combustion space adjacent to said port, said burn-elf passage comprising at least a portion which is inclined obliquely with respect to the axis of said cylinder and is arranged to direct burning exhaust gases into said duct at high velocity for burning away carbon deposits at portions thereof adjacent to said port where such deposits would otherwise accumulate.

2. Carbon deposit formation preventing means according to claim 1, in which said gas guiding means comprises W311 rsurfaces ndfining .a :straight continuous burn-off passage which by-passes the edge of said port adjacent to said combustion space.

3. Carbon deposit formation preventing means accord ing to;-elaim. 2, whereiu saidlbum-oifipassage is formed in said? cylinder wall.

4:: Canbomd eposit formation preventing 1 means accord ing -toclaim 1,-wherein \said gas guiding means comprises aenosennemben disposed -within said porL and having a surfaceinclined obliquely .t-o the axis of said cylinder and extending from an edge portion of said port adjacentto said combustion space toward a lateral portion of said duct adjacent to said p0rt, said inclined surface in part defining said burn-01f passage.

References Cited in the file of this patent UNITED STATES"'PATENTS 653, 379 "'Da'ellenbach July 10, 1900 716,069 Liet Dec. 16; 1902 1,172,324 Tuttle Feb.22, 1916 1,514,476 Still Nov. -4,' 1924 

1. CARBON DEPOSIT FORMATION PREVENTING MEANS FOR AN INTERNAL COMBUSTION ENGINE COMPRISING A CYLINDER, AN EXHAUST PORT FORMED IN THE WALL OF SAID CYLINDER, AN EXHAUST DUCT COMMUNICATING WITH SAID PORT, AND MEANS DEFINING A COMBUSTION SPACE WITHIN SAID CYLINDER AND ADJACENT TO SAID PORT, SAID FORMATION PREVENTING MEANS COMPRISING EXHAUST GAS GUIDING MEANS DEFINING A CONTINUOUS BURN-OFF PASSAGE WHICH COMMUNICATES DIRECTLY BETWEEN A PORTION OF SAID EXHAUST DUCT IMMEDIATELY ADJACENT TO SAID PORT AND A PORTION OF SAID COMBUSTION SPACE ADJACENT TO SAID 